override module with an alternative implementation in the child layer

[Alan Bateman]

On 30/07/2018 10:16, Milen Dyankov wrote:
> In response to a question posted on this list [1] some time ago, Alan
> Bateman stated "You can override *any* module (except java.base) with an
> alternative implementation in the child layer". Is that true for the
> standard JDK modules? If so, is there any documentation / code samples that
> explains how?
>
The previous thread didn't get into this but the other restriction is 
that you can't contain modules that export java.* APIs in custom layers 
(javax.* APIs are not an issue). I don't have time to give a detailed 
reply just now but look for the following in the javadoc of the 
ModuleLayer defineModulesXXX methods:

"In addition, a layer cannot be created if the configuration contains a 
module named "java.base", a configuration contains a module with a 
package named "java" or a package name starting with "java.", or the 
function to map a module name to a class loader returns null or the 
platform class loader"

-Alan.